machinegods.com

Here's a class that will create a bitmap of a window. Just pass in the Win32 handle to the window, and get a bitmap back!

Note that if a window is minimized, you generally won't get the actual contents, but rather usually a picture of the minimized task bar icon.

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Text;
using System.Runtime.InteropServices;

/*
LICENSE

Copyright (c) 2009, Michael Lehman (http://www.machinegods.com)
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* Neither the name of the Michael Lehman, machinegods.com, nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

namespace MachineGods
{
public class WindowScreenShot
{
//pinvoke.net ftw

//----------------------------------------------------------------------------
internal enum TernaryRasterOperations : uint
{
SRCCOPY = 0x00CC0020,
SRCPAINT = 0x00EE0086,
SRCAND = 0x008800C6,
SRCINVERT = 0x00660046,
SRCERASE = 0x00440328,
NOTSRCCOPY = 0x00330008,
NOTSRCERASE = 0x001100A6,
MERGECOPY = 0x00C000CA,
MERGEPAINT = 0x00BB0226,
PATCOPY = 0x00F00021,
PATPAINT = 0x00FB0A09,
PATINVERT = 0x005A0049,
DSTINVERT = 0x00550009,
BLACKNESS = 0x00000042,
WHITENESS = 0x00FF0062
}
//----------------------------------------------------------------------------
[Serializable, StructLayout(LayoutKind.Sequential)]
internal struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;

public RECT(int left_, int top_, int right_, int bottom_)
{
Left = left_;
Top = top_;
Right = right_;
Bottom = bottom_;
}

public int Height { get { return Bottom - Top; } }
public int Width { get { return Right - Left; } }
public Size Size { get { return new Size(Width, Height); } }

public Point Location { get { return new Point(Left, Top); } }

// Handy method for converting to a System.Drawing.Rectangle
public Rectangle ToRectangle()
{ return Rectangle.FromLTRB(Left, Top, Right, Bottom); }

public static RECT FromRectangle(Rectangle rectangle)
{
return new RECT(rectangle.Left, rectangle.Top, rectangle.Right, rectangle.Bottom);
}

public override int GetHashCode()
{
return Left ^ ((Top << 13) | (Top >> 0x13))
^ ((Width << 0x1a) | (Width >> 6))
^ ((Height << 7) | (Height >> 0x19));
}

#region Operator overloads

public static implicit operator Rectangle(RECT rect)
{
return rect.ToRectangle();
}

public static implicit operator RECT(Rectangle rect)
{
return FromRectangle(rect);
}

#endregion
}

//----------------------------------------------------------------------------
[StructLayout(LayoutKind.Sequential)]
internal struct WINDOWINFO
{
public uint cbSize;
public RECT rcWindow;
public RECT rcClient;
public uint dwStyle;
public uint dwExStyle;
public uint dwWindowStatus;
public uint cxWindowBorders;
public uint cyWindowBorders;
public ushort atomWindowType;
public ushort wCreatorVersion;
}
//----------------------------------------------------------------------------
[DllImport("user32.dll")]
internal static extern bool GetWindowInfo(IntPtr hwnd, ref WINDOWINFO pwi);

[DllImport("gdi32.dll")]
internal static extern bool BitBlt(IntPtr hObject, int nXDest, int nYDest, int nWidth,
int nHeight, IntPtr hObjSource, int nXSrc, int nYSrc, TernaryRasterOperations dwRop);

[DllImport("user32", ExactSpelling = true, SetLastError = true)]
internal static extern IntPtr GetWindowDC(IntPtr hWnd);

[DllImport("user32", EntryPoint = "ReleaseDC", SetLastError = true)]
private static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);

//----------------------------------------------------------------------------

public static Bitmap Get(IntPtr hWnd)
{
WINDOWINFO winInfo = new WINDOWINFO();
bool ret = GetWindowInfo(hWnd, ref winInfo);
if (!ret)
{
return null;
}

int height = winInfo.rcWindow.Height;
int width = winInfo.rcWindow.Width;
if (height == 0 || width == 0) return null;

Graphics frmGraphics = Graphics.FromHwnd(hWnd);
IntPtr hDC = GetWindowDC(hWnd); //gets the entire window
//IntPtr hDC = frmGraphics.GetHdc(); -- gets the client area, no menu bars, etc..

System.Drawing.Bitmap tmpBitmap = new System.Drawing.Bitmap(width, height, frmGraphics);
Graphics bmGraphics = Graphics.FromImage(tmpBitmap);
IntPtr bmHdc = bmGraphics.GetHdc();

BitBlt(bmHdc, 0, 0,width, height, hDC, 0, 0, TernaryRasterOperations.SRCCOPY);

bmGraphics.ReleaseHdc(bmHdc);
ReleaseDC(hWnd, hDC);

return tmpBitmap;
}

//----------------------------------------------------------------------------
}
}